One in eight children with confirmed TB has drug-resistant TB in Cape Town, South Africa, according to a surveillance study of childhood TB drug-resistance, presented by Professor Simon Schaaf at the 46th Union World Conference on Lung Health held in Cape Town from 2 to 6 December 2015.
Twenty per cent of multi-drug resistant TB cases were also found to be resistant to ofloxacin, which has important implications for the second-line treatment regimen in South Africa, which also contains the drug.
Ofloxacin is a broad-spectrum antibiotic and the active ingredient of Exocin, Octin, Tafloc, Tarivid and Zanocin.
The findings come from a prospective surveillance study conducted from March 2013 to February 2015 at the Tygerberg Children’s Hospital in Cape Town.
Drug-sensitivity was conducted using line probe assay for isoniazid and rifampicin (antibiotics used as first-line treatment of tuberculosis) and on the first isolate from each child under 13 years of age who had culture-confirmed TB.
Further phenotypic drug-sensitivity testing (tests to determine if the person is resistant to the drug) was done if rifampicin resistance was found.
If an Xpert MTB/RIF test was positive and indicated rifampicin resistance, but culture-negative, no further drug-sensitivity testing was possible.
Results were compared with five previous two-year surveys conducted at the same hospital.
Of the 292 children who had culture- or Xpert MTB/RIF-positive results for TB who were included in the study, 16 (5.5%) were found to be Xpert-positive but culture negative and were not included in the analysis. The median age was 35.5 months (IQR: 14 – 82 months) and 49% (n=143) were male.
Comparison of results
12.7% (n=35) were diagnosed with drug-resistant TB.
Four per cent (n=11) died while in hospital, eight of whom died in within the first week of hospital admission.
When comparing the results from the 2013-2015 survey to the five previous drug-resistance surveys conducted at the hospital, of the cases found to be drug-resistant, there was a significant decrease in the proportion of isoniazid mono-resistance from 2.5 % in 2013-2015 compared to 7.7% in 2005-2007 (p=0.0007).
Rifampicin mono-resistance increase from no cases in 2003-2005 to 2.9% (n=8) of cases in 2013-2015 (p=0.002).
Although there has been a significant twofold decrease in the proportion of multidrug-resistant (MDR) cases between 2007 to 2009 (8.9%) and 2011 to 2013 (4.6%) [OR: 2.01; 95% CI: 1.04-3.88, p=0.04], this decrease was not sustained in the latest survey, when it rose to 7.2%.
There had been a significant decrease in the number of cases who had previously been on TB treatment, from 22.3% (n=65) in 2005-2007 to 10.1% (n=28) in 2013-15; OR 2.55 (95% CI: 1.58 – 4.11, p<0.0001).
HIV prevalence decreased significantly from 29% to 15.5% between the 2005-2007 survey and the 2013 to 2015 survey (OR1.56; 95% CI:1.01 –4.11, p<0.05). There was also a significant increase in the proportion of children tested for HIV over the same period from 59% (n=174) to 95.7% (n=264).